Shear rates investigation in a scraped surface heat exchanger

Mabit, Jérôme; Fayolle, Francine; Legrand, Jack

doi:10.1016/j.ces.2003.07.001

Cited by 18 publications

(9 citation statements)

References 17 publications

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“…Another methodology to estimate an average shear rate in the SSHE is using the Couette analogy described by Steffe [35], and used by Benkhelifa et al (2008). The proposed by Mabit et al [36] is one of the most employed. This model consists in estimating the shear rate in two important areas within the SSHE.…”

Section: Calculation Of Average Shear Rate In the Sshementioning

confidence: 99%

Estimation of Ice Cream Mixture Viscosity during Batch Crystallization in a Scraped Surface Heat Exchanger

et al. 2020

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Ice cream viscosity is one of the properties that most changes during crystallization in scraped surface heat exchangers (SSHE), and its online measurement is not easy. Its estimation is necessary through variables that are easy to measure. The temperature and power of the stirring motor of the SSHE turn out to be this type of variable and are closely related to the viscosity. Therefore, a mathematical model based on these variables proved to be feasible. The development of this mathematical relationship involved the rheological study of the ice cream base, as well as the application of a method for its in situ melting in the rheometer as a function of the temperature, and the application of a mathematical model correlating the SSHE stirring power and the ice cream viscosity. The result was a coupled model based on both the temperature and stirring power of the SSHE, which allowed for online viscosity estimation with errors below 10% for crystallized systems with a 30% ice fraction at the exit of the SSHE. The model obtained is a first step in the search for control strategies for crystallization in SSHE.

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Section: Calculation Of Average Shear Rate In the Sshementioning

confidence: 99%

Estimation of Ice Cream Mixture Viscosity during Batch Crystallization in a Scraped Surface Heat Exchanger

et al. 2020

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“…The testing shear rates here are in the typical range of many heat energy systems such as surface heat exchangers (10–10 3 s –1 ) . The smaller emulsion droplet diameter at the chip outlet compared to the diameter at the inlet indicates that the shear force helps to maintain the emulsion fluid mechanical stability.…”

Section: Resultsmentioning

confidence: 99%

“…The testing shear rates here are in the typical range of many heat energy systems such as surface heat exchangers (10−10 3 s −1 ). 49 The smaller emulsion droplet diameter at the chip outlet compared to the diameter at the inlet indicates that the shear force helps to maintain the emulsion fluid mechanical stability. According to Stoke's law, a smaller emulsion droplet size has a lower rising velocity (u ∝ D 2 ), which leads to a lower chance for emulsion droplets to coalesce and cream.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Accelerating Fluid Development on a Chip for Renewable Energy

et al. 2020

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From physical property measurement to modelling pore-scale environments, the study of fluids at the microscale is key to understanding and optimizing fluids for large-scale energy applications. Silicon-glass microfluidics is now a proven technology for chemical effectiveness testing in the conventional oil and gas energy sector. We see potential to apply microfluidic fluid characterization technology to renewable sectors, such as geothermal and solar thermal energy recovery where fluid customization is central to performance. Key to unlocking performance gains in these renewable energy systems are phase change material slurries (PCSs)fluids that exhibit a high apparent specific heat capacity. However, testing PCS synthesis recipes is currently a slow and expensive process, given the challenges of dynamic testing at process-relevant temperatures and pressures. In this work, we develop and test a robust silicon microfluidic device and measure important PCS emulsion properties including (i) viscosity, (ii) shear stability, (iii) phase change temperature/hysteresis, and (iv) phase change stability under dynamic conditions where tests are performed quickly (<1 h) and require only minimal test fluid volumes.

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“…As shown in Figure 1, microelectrodes were not positioned on the same radial axis. The time-evolution of the diffusion current and the signal given by the optical fibre for the detection of blade passage allows association of the evolution of the diffusion current given by each microelectrode to the blade passage [15]. In our case, blade no.…”

Section: Resultsmentioning

confidence: 99%

“…All dimensions are given previously [14,15]. The scaled-down model was used to measure shear stress and understand hydrodynamic behaviour.…”

Section: Scaled-down Model Of Sshementioning

confidence: 99%

Determination of heterogeneities in a scraped surface heat exchanger using electrochemical sensors

2005

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An experimental investigation of a scaled-down model of an industrial exchanger, using an electrochemical technique, was undertaken in order to show the presence of hydrodynamic heterogeneities at low axial Reynolds number. Heterogeneities were revealed in the bowls with respect to the generalised Taylor number as the result of the perturbations added to the flow by blade rotation at both ends of the exchanger. Shear heterogeneities associated to flow visualisations were correlated to temperature heterogeneities observed in the bowls. Shear fluctuations were revealed in the scraped part describing two distinctive zones at low rotation speed caused by varying viscosity in the flow field. A complex spiral flow was observed by flow visualisation characterising a mass transfer evolution comprised between these two distinctive zones at low Taylor number.of the microelectrode (m) d h hydraulic diameter (m) d h = (d s -d r ) d r rotor diameter (m) d s stator diameter (m) e gap (m) F Faraday constant (A s mol )1 ) K consistency coefficient of the product (Ostwald law (Pa s n )) L stator length (m) n flow behaviour index of the product (Ostwald law (-)) N rotation speed (rps) n L number of blades (-) Q flow rate (m 3 s )1 ) Re ax ¼ &U d d h axial Reynolds number (-) Re axg ¼ &U 2Àn d d n d K generalised axial Reynolds number (-) Re r ¼ &Nd 2 r Rotational Reynolds number (-) R r rotor radius (m) R s stator radius (m) S wall shear rate (s )1 ) Sc exchange surface (m 2 ) T temperature (°C) Ta ¼ ffiffiffiffiffiffiffiffiffiffi R s ÀR r R r q &d h 2 ðR r Þ Taylor number (-) Ta g ¼ ffiffiffiffiffiffiffiffiffiffi R s ÀR r R r q &d n h 2 n ðR r Þ 2Àn K generalised Taylor number (-) Ta c , Ta gc critical values of Taylor number (-) U d mean axial velocity in the annular space (m s )1 ) z number of electrons (-) q density (kg m )3 ) g dynamic viscosity (Pa s) cshear rate (s )1 ) X rotating speed of the rotor (rad. s )1 ); X = 2pN s shear stress (Pa)

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Shear rates investigation in a scraped surface heat exchanger

Cited by 18 publications

References 17 publications

Estimation of Ice Cream Mixture Viscosity during Batch Crystallization in a Scraped Surface Heat Exchanger

Estimation of Ice Cream Mixture Viscosity during Batch Crystallization in a Scraped Surface Heat Exchanger

Accelerating Fluid Development on a Chip for Renewable Energy

Determination of heterogeneities in a scraped surface heat exchanger using electrochemical sensors

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